The invention relates generally to hydrogen purification systems and more particularly to hydrogen-selective membranes, methods for forming membrane modules containing a plurality of hydrogen-selective membranes, and hydrogen producing and purifying systems containing the same.
Hydrogen-selective membranes formed from hydrogen-permeable metals, most notably palladium and alloys of palladium, are known. In particular, planar palladium-alloy membranes have been disclosed for purifying hydrogen gas streams, such as hydrogen gas streams produced by steam reformers, autothermal reformers, partial oxidation reactors, pyrolysis reactors and other fuel processors, including fuel processors configured to supply purified hydrogen to fuel cells or other processes requiring high-purity hydrogen.
To be economical, palladium and palladium-alloy membranes must be thin. For example, planar membranes are typically approximately 0.001 inches thick. However, these extremely thin membranes are subject to wrinkling during assembly into a membrane module containing one or more hydrogen-selective membranes. A membrane that has one or more wrinkles is subject to premature failure due to stress fractures forming at the wrinkle. When such a failure occurs, impurities that otherwise would be unable to pass through the membrane can now pass through the membrane, thereby reducing the purity of the product hydrogen stream and potentially damaging the fuel cell stack or other hydrogen-consuming device with which the purified stream is used.
Therefore, there is a need for a method for preparing hydrogen-selective membranes for use in a fuel processor or other hydrogen-purifying device without wrinkling the membranes.
The present invention is directed to membrane modules that contain one or more hydrogen-selective membranes, methods for preparing the same, and hydrogen purification systems, fuel processors and devices containing the same. In some embodiments, the membrane modules include one or more hydrogen-selective membranes supported on a support or screen structure, of which a variety of embodiments are disclosed. In some embodiments, the membrane or membranes are adhesively mounted on the screen structure during assembly. In some embodiments, the screen structure includes a plurality of screen members adhesively mounted together during assembly. In some embodiments, the screen structure includes a coating.